The present invention relates to catheters for percutaneous transluminal use. More particularly, the present invention relates to low profile catheter shaft designs for use with catheters intended for accessing remote or tortuous vascular locations.
A wide variety of interventional procedures have been developed which require access to remote parts of the vascular system. One increasingly utilized coronary revascularization procedure, for example, is percutaneous transluminal coronary angioplasty (PTCA). In a typical PTCA procedure, a guiding catheter having a prebent distal tip is percutaneously introduced at a remote location such as the femoral artery using a conventional Seldinger technique. The guide catheter is advanced retrograde until it reaches the ascending aorta with the distal tip seated in the ostium of a desired coronary artery. Steering is accomplished during transluminal advancement by torquing the proximal end of the guide catheter as needed until the distal tip is positioned in the ostium.
An elongate, flexible guidewire is then advanced through and out the distal end of the guide catheter, and negotiated through the tortuous vasculature of the coronary arteries until it crosses a lesion to be dilated. A dilatation catheter is thereafter advanced along the guidewire until the dilatation balloon is positioned within the lesion.
Once properly positioned, the balloon is inflated one or more times to an inflation pressure on the order of six to twelve atmospheres or higher to dilate the lesion. Balloon catheters sized for the coronary arteries may inflate to a diameter in the range of from about two to about four cm. Following dilatation, the balloon is deflated and the catheter is proximally withdrawn from the patient.
Considerable effort has been devoted to reducing the profile and improving the trackability (flexibility) of PTCA and other interventional catheters. Improvements of this nature can enable the catheter to reach more remote and smaller treatment sites. These capabilities can permit treatment of both more remote coronary arteries as well as other narrow and tortuous vessels such as within the intracranial vasculature.
A further requirement of a successful dilatation or other therapeutic or diagnostic catheter is that the catheter shaft exhibit sufficient pushability. Pushability relates to the longitudinal transmission of force along the axial length of the catheter from the proximal end to the distal end. This characteristic is necessary to enable the physician to advance the catheter against resistive forces such as due to the tortuous path and small diameter of the vessel and target stenosis.
Notwithstanding the significant research effort in this technology, there remains a need for a catheter shaft design which minimizes the crossing profile and yet retains sufficient columns strength and torquability for the intended clinical objective. Preferably, the catheter shaft design can be adapted for any of a variety of functional applications, such as balloon dilatation and or drug or stint delivery catheters, either in an over the wire or a rapid exchange configuration.
There is provided in accordance with one aspect of the present invention a low profile balloon catheter. The catheter comprises an elongate flexible tubular body, having a proximal section and a distal section. An inner collapsible tubular wall is provided in the distal section, for defining a guidewire lumen. An outer tubular wall concentrically disposed about the inner tubular wall defines a potential inflation lumen in between the inner tubular wall and the outer tubular wall. An inflatable balloon is provided on the distal section, in fluid communication with the inflation lumen.
In one embodiment, the catheter further comprises a transition between the proximal section and the distal section. The transition is at least about 3 cm from the distal end of the catheter.
In accordance with another aspect of the present invention, there is provided a method of performing a medical procedure on a patient. The method comprises the steps of providing a catheter having a distal section in which a first lumen is defined within a first collapsible tube, the first tube positioned within a second outer tube, and a second lumen is defined in a space between the first tube and the second tube. The guidewire is advanced through the patient to a site for performing the medical procedure. The catheter is advanced along the guidewire to the site, with the guidewire extending through the first lumen, wherein the first tube, second tube and guidewire are dimensioned such that when the guidewire is positioned within the first tube, the first tube substantially fills the second tube.
The catheter is positioned within the patient to perform the medical procedure at the site, and the guidewire is thereafter proximally withdrawn from at least the distal section of the catheter. At least a distal portion of the first tube is permitted to collapse, thereby increasing the available cross-sectional area of the second lumen. Media is thereafter introduced through the second lumen to treat the site.
In one embodiment, the catheter further comprises an inflatable balloon in fluid communication with the second lumen, and the introducing media step comprises introducing inflation media through the second lumen to inflate the balloon. In another embodiment, the catheter further comprises a plurality of drug delivery ports along the length of the catheter shaft, and the introducing media step comprises introducing drug through the second lumen to deliver the drug to the site.
In a further embodiment, the catheter comprises a transition between the proximal section and the distal section, and the withdrawing the guidewire step comprises withdrawing the distal end of the guidewire to a position between the distal end of the transition and the proximal end of the catheter. Preferably, the withdrawing the guidewire step comprises withdrawing the distal end of the guidewire to a point within the range of from about 3 cm to about 35 cm from the distal end of the catheter.
In accordance with a further aspect of the present invention, there is provided a method of dilating a stenosis in a vessel. The method comprises the steps of providing a balloon dilatation catheter having a distal tubular shaft section with an axially extending, laterally movable wall separating a first side of the movable wall from a second side of the movable wall. The catheter is axially slidably mounted on a guidewire, and percutaneously introduced and transluminally advanced along the guidewire such that the guidewire is on the first side of the movable wall.
The balloon is positioned at the stenosis, and the guidewire is withdrawn from the distal tubular shaft section. Inflation media is introduced through the catheter and along the second side of the movable wall to inflate the balloon. A first lumen in the distal section on the first side of the movable wall has a relatively greater cross-sectional area than a second lumen on the second side of the movable wall during the positioning step, and the second lumen has a relatively greater cross-sectional area than the first lumen during the introducing inflation media step.
In accordance with a further aspect of the present invention, there is provided a method of treating a patient. The method comprises the steps of providing a catheter having a guidewire lumen and at least a second lumen extending therethrough. A distal end of a guidewire is positioned in a patient, and the catheter is advanced over the guidewire and into the patient. The distal end of the guidewire is retracted to a position within the catheter, and media is thereafter introduced through the second lumen to treat the patient.
In one embodiment, the cross-sectional area of a portion of the second lumen is enlargeable following the retracting the distal end of the guidewire step. The introducing media step may comprise introducing inflation media for inflating a balloon, or introducing medication through the second lumen.
In accordance with a further aspect of the present invention, there is provided a method of dilating a stenosis in a body lumen. The method comprises the steps of providing a balloon dilatation catheter having at least a guidewire lumen and an inflation lumen extending therethrough. The balloon is positioned in the body lumen to dilate the stenosis, and a distal portion of the guidewire lumen is collapsed by introducing inflation media through the inflation lumen.
Further features and advantages of the present invention will become apparent from the detailed description of preferred embodiments which follows, when considered with the attached drawings and claims.